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Next Audioserve Version

As I’m using audioserve for almost a year, I’m becoming quite keen about it – it’s exactly what I wanted – simple, lightweight and works as I needed. With it listening to audiobooks is just a simple pleasure. Recently I updated audioserve server with couple more features, which might not be essential, but can be useful: multiple transcoding formats  ( meaning target formats) and transcoding cache. Continue reading Next Audioserve Version

Sqlite3 – How Slow Is Write?

Sqlite3 is lightweight relational database, mainly focused on smaller local systems. Being used in Android it’s now probably most spread relational database in world with billions of instances running. Lite in the name means that it is not client-server architecture and it’s intended for lower data volumes – ideal usage profile is read mostly, with occasional writes. Sqlite3 is often used as an embedded data store in various applications (Firefox and Chrome are most prominent ones). Recently I’ve been playing a bit with sqlite3 interface in Rust and had run couple of simple tests especially focused on writes. So how does sqlite3 performs and how it compares with other more typical client-server RDBMS like PostgreSQL?  It’s not any serious benchmark, just couple of toy tests to highlight few things. Continue reading Sqlite3 – How Slow Is Write?

Future Never Sleeps

Recently I’ve been reading this book:  “Network Programming with Rust” by Abhishek Chanda. I found this book bit problematic. It’s just collection of many unrelated examples (often taken from crates documentation), with just little of background and concepts explanation and in some parts this book is just wrong, in other parts it’s using too much simplifications, so the result does not make much sense or worst it introduces some dangerous ideas. One of these  places is part about futures and streams – let’s look at one example: Continue reading Future Never Sleeps

Fearless Upgrades with Typed Languages

One of many advantages of statically typed programing languages like Rust or Java is their resilience to changes in dependent libraries, usually caused by new library versions with modified interface – e.g. the major version changes. In statically typed language we usually see problems in compile time and it should be relatively easy to fix, but in dynamic languages such as Python or Javascript upgrade is more challenging and problems  demonstrate themselves during tests (in better case, when we have good test coverage) or in production in worst case. I had recently came through this process for couple of  relatively small projects in Rust. Couple of dependencies (hyper and tokio) had been upgraded to new versions with significant changes to their interface. With update compilation broke with tens of errors, but gradually I was able to fix all of them (in one case it required to improve error handling with custom error type, plus using additional new library, as typed headers were removed form hyper) and after code compiled and run through basic tests I was pretty sure that I’m fine with new libraries. In similar situation in python I would need much more work to be sure that code works after such major upgrade of dependencies. In practice it enables easier maintenance of code and less effort  to keep it up to date with latest libraries. For library authors it provides more freedom and they can introduce breaking changes more often (with great cargo build tool in Rust library users can pin themselves to older version, if they do not want to upgrade).

From Ignorance to Enlightenment – Playing with Tokio

I have been playing with tokio already in couple of small projects (ptunnel-rust and indirectly (via hyper) in audioserve), but I cannot say that I’m proficient.  Also tokio is very much moving target –  what I used couple month ago is already bit outdated now(old version is tokio_core crate – where default executor was on current thread, now it’s work stealing thread pool). So I decided to refresh and deepen my knowledge and created a toy project –  stupid jokes server –  it’s a TCP sever, which sends a random  joke to client after it connects and then closes connection. Jokes are stored in text file, separated by dashed lines.  My main interest was to test how to use local file system I/Os, which are blocking by nature, with tokio asynchronous approach (so I initially skipped easiest and probably most efficient implementation, where all jokes would be cached in memory).  Usually in a real project you’ll have some blocking code, so I need to know how to handle it. This article is history of my attempts (and failures) recorded in a hope that it might help others in learning tokio (and also writing it down helped me to absorb gained knowledge). Continue reading From Ignorance to Enlightenment – Playing with Tokio

How much better is the thread pool?

Is thread pool worth to consider for my project?   I was  looking for some opinions around the net and as usual they  differ and most common wisdom is it matters. Generally it’s “known” that creating and tearing down thread is “significant” overhead, so if you have a lot of small tasks thread pool is much better solution then spawning new thread for each task.  But what is significant overhead?  According to what I read time to create thread on Linux should be about 10μs (which does not look as too much to me) and app. 2MB of memory allocated for stack (configurable).   I was considering thread pool in context of audioserve project, where I started with simplest possible solution (e.g. spawning individual threads ) and was wondering how much I’m loosing by not using thread pool. So I implemented simple thread pool (as learning exercise – long term audioserve solution should use tokio-threadpool)  and add it to audioserve.  In the remainder of this short article I’d like to share my findings and  roughly quantify benefits of thread pool for such small project. Continue reading How much better is the thread pool?

audioserve Android Client Early Beta Is Available

So finally there is something. I’m using it myself now to listen to audiobooks and it have almost all functionality I wanted it to have. It might be still bit unstable and few things is not well behaving (keep up long time in paused state, navigation between notifications and activities is still bit messy and few more issues), but generally it works. Continue reading audioserve Android Client Early Beta Is Available

Stupidly Complex or Completely Stupid – Android Development

As part of audioserve project I decided to create an Android client. To make this exercise more interesting I decided to write it in Kotlin language (see previous article about Kotlin language).  This client should provide roughly similar interface as web client (see this article for web client interface demo), but I hoped to achieve much better caching features, which will enable to play smoothly even when connectivity is temporarily lost ( for half an  hour, an hour) and possibility to download and play audiobooks completely offline.  Further in this article I’d like to share my experiences with Android development, as beginner in this area.  And spoiler is I do not like it. Continue reading Stupidly Complex or Completely Stupid – Android Development